advice needed on robotic armature

A project I'm working on entails a medical skeleton's forearm, laying
flat on a table, which needs to rotate left and right in order to point
to various items on the table. Currently, I have a hole drilled in the
tabletop, with an extra-strength servo mounted underneath. The servo
gear sticks up through the hole, where it is screwed to the 'elbow' of
the skeletal arm, and can motivate the arm as needed.
So far so good, but the servo has to overcome an awful lot of friction
when pointing the arm at something. Would anyone be able to recommend
some kind of turntable or other setup, which could support the arm up
off the table, just high enough to eliminate most of the friction,
while allowing a servo gear to still attach at the 'elbow' and do its
job? I'm guessing that an extension of some kind might also be needed
to make the connection from the servo up through the middle of the
turntable to the arm....
Thanks in advance,
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You may want to go to your local hardware store and check out a lazy susan bearing. You could make a cheep platform to work with your project.
Reply to
WalMart has a plastic lazy susan gizmo for ~$2.50 that lays flat and is ~10" across (roller bearings are around the outside edge). For projects needing to rotate heavier objsects I've looked at spacing it up off the surface around its edges such that a servo could be underneath and rotate it 180 deg with out the servo having to support the weight above it.
Reply to
Si Ballenger
"Alex" wrote in news:1141955955.420300.77590
You could put a caster wheel or ball at some point along the arm. A piece of plastic (UHMW, Delrin or probably anything) as a skid might also work. Perhaps one of those slippery disks they sell in packages at Home Depot for putting on the bottom of things you want to slide around.
Reply to
Mitch Berkson

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